Growth of M-plane GaN(1(1)over-bar-00): A way to evade electrical polarization in nitrides

We investigate the growth of M-plane GaN(1 (1) over bar 00) on gamma-LiAlO2 (100) by molecular beam epitaxy. The crystal orientation and structural pro perties of buffer layers are examined by means of reflection high-energy el ectron diffraction, high-resolution transmission electron microscopy, X-ray diffraction, Raman scattering, and atomic force microscopy. The layers are shown to be single-phase GaN(1 (1) over bar 00) within the measurements' s ensitivity. In contrast to the ubiquitous C-plane GaN[0001] orientation, th e M-plane of wurtzite nitrides is free of electrical polarization. This is experimentally verified for (Al,Ga)N/GaN heterostructures by continuous-wav e and time-resolved luminescence.